Pressure loaded gear pump



Nov. 6, 1956 F. E. NORLIN PRESSURE: LOADED GEARv PUMP Filed Sept. 28, 1953 United States PatentY 2,769,396, PRESSURE LOADED (manl com.

Francis E. Norlin, Chesterland, Ghio, assigner` tolorgi-` Warnerj Corporation, Chicago, lll., a corporation of Illinois Application September 2S, 1953, Serial No. 382,682.. 17 Claims. (Cl. 103.-126) This invention relates to pressure loaded gear pumps and more particularly to an arrangement for insurmg proper location of the pressure loadable bushings in a pressure loaded type interrneshingk gear pump.

In a pressure loaded, intermeshing gear type pump having one or more sets of axially movable, pressure loadablebushings, a part of the output or dischargepressure ofthe pump is appliedv to the rear or motive surfaces of the axially movable bushings to urge these bushings into sealing engagement with their associated gears. As disclosed in U. S. Patent No. 2,420,622 toLauck et al., byV carefully selecting the relative areas oftheforward surfacesof the bushings, it is-possible to control within very close'limits the actual sealing pressure provided. In practice, this requires a somewhat highereffective' pressure in the direction tending to establish the seal than in the direction tending to open the seal.

In the usual form of pressure loaded pumps, the p ressure loadable bushings must remain movable and, becauseof this, a certain'minitnumrclearance must be; provided between the sides of the-bushings-and the-adja cent sides of the chambers or bores yin Athe pump housing in which the bushings are received; In practice, this clearance is actually Very slight, butit has beenfoundV that Asince thebushingsmay move, either toeone side' or to the other of the chamber, during fassernbly, koccasionally a pump will be made in which the clearance of the bushings adjacentthe corresponding reduction inclearance'adjacent the discharge side ofl thepump which is maintained during operation of the pump by ay shifted alignment of the housing, as assembled, to provide a substantialleakage path to inletfpressure. This, of course, materially reduces the efficiency of therpump. j

As `disclosed in theearlier iled application of John A. Lauck, Serial No. 178,925, iiledAugust-lll, 1950, now Patent No. 2,660,958, it is possibleto preloea'te the bushings in the pump by associating withV the flanged 'portions of each of the pressure loadable bushings a radially disposed pressure plunger or detentso located `as to urge the anged portions towards the inlet side'ofthe pump. 'This arrangementhas been found.to be satisfactory=1and1the present invention is directed to an improvement thereover where it is deemed necessary to provide more widely directedpressure forces, that is, pressure yforces .overv a substantial portion of the iianged portions of the bushingson thedischarge .side of the pump to urge the iianged portions of the bushings toward the inlet side ofthe pump.

Accordingly, anobject ofthe present inventionvis to provide a new and. improvedpressureloadedftype intermeshing pumpV incorporating means for insuring the location of the pressure loaded bushings adjacent the'inlet side Aof the pump to substantially reduce leakagevthereat.

Another object of the present invention is to provide a new and improved pressure loaded'vtypejinternreshing gear pump utilizing means for'substantiallyreducing the leakage adjacent the inlet side'of the pump byincOrpOrating means disposedover the major portionof; thefiianged "ice 2; portionofthe bushings, to Iurge these flanged portions towards inlet pressure.

A furtherobject of the present invention is to provide;` in a. pressure loadedv type intermeshing gear pump,l a` means `for insuring againstleakage adjacent theginlet sidel of the. pumpgby providing a means which cooperateswithf4 the flanged portions ofthe bushingsV and the adjacent housing to urge the bushings towards the'inlet side of thereof a peripherally disposedring segn 1ent-.made .of.y rubber or other rubber-like,resilientmaterial'fso located.-

as to urge the flanged portiony ofitsfassociated-bushing towardthel inletnside' of; the pump, This-rubber ring,y

segmenLmay-A be. inserted feitherin al recessin the anged portion of the bushing or maybe Vcarried 'in suitable Arecesses formedin the-housing, sucient minimum.depth beinggprovided so -I that thisfringA isV continuously under. compression.`

In accordance with a second embodiment of thisine vention,` a pressurev loadablegear type pump having at least, one` set of laxially movable-pressure lOadabIe, flanged bushings; has associated with-the flanged portions thereof' a-peripherally'disposed metallic ring segment having.ra

diallyp` disposedy springypressed meansso locatedV as tov continuously urge the flangedportions of thedbushing to.- wardsthe-inlet'side of the pump, This ring segmentmay be received in., recesseseitherV iny the,v `flanged portionx off the bushings'l or` carried in. assuitable .recess :formed A in the housing,

Other objeetsand advantages of the presentinvention will be-apparentfrom thefollowing detailedrdescription'` thereoftaken in conjunction-with the drawingsfwherein:

Eig-..1 is a-fragmentary, axial, sectionalview-showng to advantage a'pressure'loaded type'intermeshing: gear pumpjconstructed .in-accordance with one embodiment of this invention;

Fig. 2, is a transverse, cross sectional lview taken esubstantially. along line ZTZ-OfFig. 1 and showing-toadvantage the arrangementof the; peripherally.v disposed resilient, rubber-likel ring segment; and.

Fig.. 3.is .a Viewv similar to Fig. land showing vto ad-. vantargethe second embodiment of this invention, namely, the arrangement ofthe peripherallyy disposed metallic ring.y segment with the: radially4 disposed spring; pressed meansto. urge. the. bush-ings ltowards the, inlet ,side` of the pump.

Referringnowto thedrawings and particularly; t0 Fig. l

v thereof, a pumpgenerally similar to that 'shownin the aforementioned Lauck etal. Patent No. 2,420,622 isillustratedcomprising asectional fhousingtlwith a mainjb'ody portion10.andaclosure; ory cover member 1'1. These -sections arefnormallyl boltedftogether and` cooperateito define -therewithin intersecting bores or pumping gear chambers 12.and13; respectively, said bores orjch'arn-bers having; parallelaxes and arranged to receive in comple.` mentary relationship.in-termeshingI pumpingvgears l14*r and lrespectively. In the embodiment illustrated;` thepunipimg .gearshave integrally formed-therewith hollow shafts 16' and 17, respective1y,and the left portion of the shafts 16:-,and `17- Iare journaledfin .anged bodyl bushings 1S=and 19 mounted inthe. left portions of the pumping gear chambers 12 and 13.r The right portions of the gear, are journaled, respectively, in' axially adjustable, pressure loadablejanged bushings22 and 23 mounted in-the right side -of the pumping gear chambers. In theembodiment illustrated, the `upper pumping member 15;'y is. the drivinggear. and. is.. rotated in. .a .clockwise direction, as viewed in Figs. 2 and 3. In accordance with conventional pump design practice, the gear shaft on the upper gear may be extended to the left, as viewed in Fig. l and coupled to a suitable source of power (not shown). Low pressure liquid is introduced into the pump housing through inlet 24 formed in the left side of the pump housing, as seen lin Figs. 2 and 3, and high pressure liquid is discharged from the pump housing through outlet 25 formed in the right side of the housing, the inlet and outlet port communicating with the inlet and discharge areas of the intermeshing pumping gears. The pressure loadable bushings are normally fitted into the bores with sufficient clearance to permit slight Iaxial movement of the bushings with respect to the bores to establish the desired pressure loaded seal during operation of the pump.

In the operation of a pump of this type, discharge pressure generated by the intermeshing gears may be communicated from the outlet or discharge side thereof to the annular pressure loading areas 26 and 27, often referred to as rear or motive pressure areas, located at the back of the hanged portions of the bushings, through an axially extending passage 28 formed in a periphery of the flanged portions of the bushings on the discharge side of the pump at the point of convergence of the flanges of the bushings with the pump housing. Areas 26 and 27 cooperate with the adjacent walls of the housing bores 12 and 13 and the peripheries of the barrel portions of the bushings to define annular pressure loading chambers 30 and 31, respectively. The passage 28 extends from the discharge side of the gears to the right as viewed in Fig. 1 to the inner cornmunicating portions of the pressure loading chambers 30 and 31 at their point of juncture.

The escape of pressure rearwardly from the pressure loading areas is substantially prevented by means of O- ring seals 32 disposed about the periphery of the tubular or barrel portions of each bushing in suitable annular grooves formed in the periphery of the bushing or in the adjacent bore wall. Pressure leaking past the O-ring seal may be vented to inlet pressure or to a zone `of intermediate pressure in accordance with conventional pressure loading pump practice, as set forth in the above-mentioned Lauck Patent No. 2,420,622, and as described in this Lauck patent, there is provided a refined balance o-f pressure between the pressure acting upon the rear `or motive surface areas 26 and 27 and the pressures acting on the forward gear engaging surfaces 33 and 34 of these bushings. Re lief recesses 35 and 36 are formed either in the forward surface of the bushing or in the gear side face, said relief recesses being vented to an area of lower than discharge pressure through an axially extending passage 37 or 38 formed in the bore of the bushings or are vented merely through a loose fit between the journal of the gear and the bore of the bushing.

In order to permit the slight axial movement required of the bushing in order to establish aforesaid seal, it is necessary to t the bushings with some clearance in the bushing receiving chambers. The bushings may be actually assembled in such a manner that more clearance is provided adjacent the inlet side of the pump than adjacent the discharge side of the pump, that is to say, that axial movable bushings may be slightly off center with respect to the axis of the bushing receiving chambers and located somewhat nearer the discharge side than the inlet side. Thus, for example, the bush-ings might be assembled so as to have metal :to metal contact with the discharge side of the pump housing inner wall, and, with the cover section thereon and bolted into position, the bushings are then maintained in metal to metal con-tact with the discharge side so that despite the generation of the pressure on the discharge side of the pump, which would otherwise tend to move the bushings toward the inlet side of the pump, the bushings are held transversely immovable by the cover and a leakage passage is provided adjacent the inlet side. Since, in the operation of the pump, pressure applied to the pressure loading surface areas 26 and 27 is substantially equivalent to discharge pressure, a leak-age path provided by the excessive clearance occurring when the bushings are positioned nearer the discharge side then the inlet port may be sucient to materially reduce the efciency of the pump.

It has been found in accordance with the present invention that this undesirable condition may be substantially eliminated by providing means for establishing during the assembly the location of the bushings in such a manner that clearance adjacent the inlet side of the pump is held to a minimum and further in accordance with this invention that this condition will be continued throughout the operation of the pump.

Referring now particularly to Fig. 2, it will be seen that recesses 41 and 42 are formed on the right side of the hanged portion of the lower and upper pressure loadable bushings 22 and 23, said recesses being located substantially midway between the pressure loadable surface areas 26 and 27 and the forward gear engaging surfaces 33 and 34 and extending from the point of convergence or juncture of the flanged portion of the bushings near the passage 28 around the periphery of the flanged portions of the bushings and slightly beyond the center or midway portion between the inlet and outlet of the pump as viewed in Fig. 2. In these recesses 4l and 42 there is received a single strip or piece of resilient rubber-like material, indicated as 43, which forms a sealing arrangement. This strip of material may be either square or rectangular in cross section and has a depth slightly greater than the depth of the aforementioned recesses 41 and 42 in the upper and lower bushings. In this manner, the rubber-like sealing ring segment is compressed against the sides of the housing wall and the base of the recesses and by virtue of this compression the bushings themselves are urged in the direction opposite to the discharge side, seating the left periphery of the ilanged portions of the bushings tightly against the side of the housing adjacent the inlet side of the pump.

It is understood that by proper selection of the cross sectional size of the rubber-like resilient material and the depth of the recesses at the periphery or cuter diameter of the flanged portion of the bushings, proper compression of the resilient material and consequent tight seating of the bu-shing near the inlet side of the pump will be provided. It is further apparent that the passage 28 may cooperate between the juncture of the bushings, the point of convergence of the housing and the ring as shown in Fig. 2, which cooperation prevents interference of discharge pressure being communicated to the rear or motive surface of the bushings. Too, when selecting size and width of this resilient rubber-like material as Well as the depth of the recesses, care must be taken to prevent interference with the axial movement of the bushings during operation of the pump.

From the foregoing it will be evident that by constructing a pump in accordance with this invention the possibility of erratic alignment of the pump will be substantially eliminated and more particularly during operation of the pump, proper positioning of the bushings is assured so that any tendency of leakage to occur adjacent the inlet side of the pump is substantially reduced.

In the other embodiment shown in Fig. 3 a similar arrangement is provided for properly sealing the flanged portions of the pressure loadable bushings to reduce the tendency of leakage around the outer periphery thereof. It will be seen in Fig. 3 that in addition to the aforementioned recesses 41 and 42, provided in upper and lower portions of the bushings as disclosed in Fig. 2, there is provided a plurality of radially disposed recesses 45 between the juncture of the flanged portions of the bushings and the midway portion of the recesses on the outer diameter thereof between the inlet and outlet of the pump.

In this embodiment, a resilient means, sh'own in the area-see drawingswin the form ot a helically coiledcompression; spring 46, is received in these recesses with one endY of these-springs, are urged towards the left or inlet side of the pump to `seat tightly against the housing prevent leakage thereat. in amannersimilar to thatshown in Fig. 2 these sealing ring segments cooperate with the juncture of the bushings and the housing on the discharge side and prevent interference or discharge pressure being. communicated to the rear or motive surface of the bushings, and ina manner similar to Fig. 2, the springs 4S and depth of the recesses 45 must be selected with care so that interference with the axial movement ofthe bushings during operation of the pump is prevented.

While in Fig. 3 only three recesses with springs therein have been illustrated in conjunction with each bushing and metallic ring segment and located substantiallyas shown, it will be evident that the location and number of these recesses may be varied. Also, while generally less convenient than that illustrated in Fig. 3, the compression springs and radially disposed recesses may be located in the housing rather than in the bushings.

From the foregoing it will be evident that the applicant has disclosed a new and improved pressure loaded pump incorporating a means f insuring against leakage adjacent the inlet side of the pump which may be caused by a clearance being provided between the flanged portions of the bushings and the adjacent bore wall during assembly and which clearance may be maintained throughout the operation of the pump.

Where herein the various parts of this invention have been referred toas being located in the right'or left position, or an upper or lower position, it will be und rstood that this is done solely for the purpose of facilitating description and that such references relate only to the relative positionsof the parts as shown in the accompanying drawings.

While but two embodiments have been shown and described, it will be evident that many changes and modiications may be made therein without departing from the spirit or scope of the present invention.

l claim:

v1. A pressure loaded type intermeshing gear pump including. a housinghaving a pumping chamber formed therein `and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshing pumping gears disposed insaid chamber, bushings operativelyl associated with each of said pumping gears, at least one of said bushings being axially movable in response to application of discharge pressure to the rear surface thereof to engage the operativelyassociated gear side face in sealing relation, and resilient means operatively associated with said axially movable bushing for urging said bushing in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of saidpump, said resilient means comprising a ring segment.

2. A pressure loaded type intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housingand an outlet port formed on the opposite sideof the housing, said ports communicating with said pumping chamber, intermeshing pumping gears disposed in said chamber, bushings operatively associated with each of said pumping gears, at least one of said bushings being axially movable in response to application of discharge pressure to .the rear surface thereof to engage the operatively associated gear side'tace in sealing: relation, and resilient means operatively associated'with said axially movable bushing for urging said-bushing in a direction substantially normal to the axis of rotation ofsaid lpump.- ing gears and towards the inlet side ofsaid pump, said resilient means comprising a rubber-like sealing ring segment.

3. A pressure loaded type intermeshing gear pump 4including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshing pumping gears disposed in said chamber, bushings operatively associated with each of.

said pumping gears, at least one of said bushings being axially movable in response to application of discharge pressure to the rear surface thereof to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with said axially movable bushing for urging said bushing in a direction substantially normal to the axis of rotation of said pumping gears and towards thel inlet side of said pump, saidfresilient means comprising a rubber-like sealing ring segment, a recess formed in the outer periphery of said bushing, said rubber-like sealing ring segment being received in said recess.

4. A pressure loaded type intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshingpumping gears disposed invsaid chamber, bushings operatively associated with` each of said pumpinggears, at least one of said bushings being axially movable in response to application of discharge pressure to the rear surface thereof to engagethe opera-` tively associated gear side face in sealing rclation,rand resilientmeans operatively associated with said axially movable bushing for urging said bushing in a direction substantially normal to the axis ofrotation of said pumping gears and towards the inlet side of said pump said resilient means comprising a rubber-like sealing ring segment, a recess formed in the outer peripheryA of said bushing, said recess extending over a greater portion of the outer periphery of said bushing, and said rubber-like sealing ring segment being received in said recess.

5. A pressure loaded type intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formedon one side of thehousing andan outlet port formed on the opposite side of the housing, said ports communicating withsaid pumping chamber, intermeshing pumpinggears disposed in said chamber, bushings operatively associated with each of said pumping gears, atleast one of .said bushings being axially movable in response to application of discharge pressure to the rear surface. thereof to engage theoperatively associated gear side tace in sealing.relationand resilient means operatively associated with said axially movable bushing for urging said bushing in a direction substantially normal to the axis ofrotation of said pumping gears and towards the inlet. side of said pump, said resilient means comprising a piston ring segment.

6. A pressure loaded type intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshing pumping gears, disposed in said chamber, bushings operatively associated with each of said pumping gears, at least one of said bushings being axially movable in response to application of discharge pressure to the rear surface thereof to engage the operatively associated gear side face in/sealing relation, and resilient means.A operatively associated with saidA axially movable bushing for urging said bushing in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of said pump, said resilient means comprising a metallic piston ring segment.

7. A pressure loaded typ'e intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshing pumping gears disposed in said chamber, bushings operatively `associated with each of said pumping gears, at least one of said bushings being axially movable in .response to application of discharge pressure to the rear surface thereof to engage the operativ'ely associated gear side face in sealing relation, and resilient means operatively associated with said axially movable bushing for urging said bushing in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of said pump, said resilient means comprising a spring pressed metallic piston ring segment subject to spring pressure for urging said piston ring segment radially outwardly.

8. A pressure loaded type intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshing pumping gears disposed in said chamber, bushings operatively associated with each of said pumping gears, at least one of said bushings being axially movable in response to application of discharge pressure to the rear surface thereof to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with said axially movable bushing for urging said bushing in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of said pump, said resilient means comprising a spring pressed metallic piston ring segment carried in a recess formed in the outer periphery of said bushing.

9. A pressure loaded type intermeshing gear pump including a housing having a pumping chamber formed therein and an inlet port formed on one side of the housing and an outlet port formed on the opposite side of the housing, said ports communicating with said pumping chamber, intermeshing pumping gears disposed in said chamber, bushings operatively associated with each of said pumping gears, at least one of said bushings being axially movable in response to application of 'discharge pressure to the rear surface thereof to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with said axially movable bushing for urging said bushing in `a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of said pump, said resilient means comprising a spring pressed metallic piston ring segment carried in the recess formed in the outer periphery of said bushing, said recess extending substantially over a major portion of the outer periphery of said bushing.

l0. A pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, lsaid ports communicating with said chamber, intermeshing pumping gears disposed in said chamber, xed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly flanged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said anged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the flanged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising a ring segment.

ll. A pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating with said chamber, intermeshing pumping gears `disposed in said chamber, iixed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly flanged, said axially movable bushings being subject to application of discharge pressure to the rear surface of lsaid flanged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the flanged portions of said axially movable bushings for urging lsaid bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising a rubber-like sealing ring segment associated with the flanged portions of said axially movable bushings.

12. vA pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating with said chamber, intermeshing pumping gears disposed in said chamber, fixed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly flanged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said flanged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the flanged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and ltowards the inlet side of the pump, said resilient means comprising a rubber-like sealing ring segment, a recess formed in the outer periphery of the flanged portion of each of said axially movable bushings, said rubber-like sealing ring segment being `disposed in said recess.

13. A pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating with said chamber, intermeshing pumping gears disposed in said chamber, ixed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly anged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said flanged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the lianged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising piston ring segments associated with the flanged portions of said axially movable bushings.

14. A pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating With said chamber, intermeshing pumping gears disposed in said chamber, xed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly anged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said anged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the flanged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising metallic piston ring segments associated with the anged portions of said axially movable bushings.

15. A pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating with said chamber, intermeshing pumping gears disposed in said chamber, fixed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly flanged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said flanged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the anged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising spring pressed metallic piston ring segments associated with the flanged portions of said axially movable bushings and subject to spring pressure for urging said piston ring segments radially outwardly.

16. A pressure loaded type intermeshing gear pump comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating with said chamber, intermeshing pumping gears disposed in said chamber, xed bod)7 bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly flanged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said flanged portions to engage the operatively associated gear side face in sealing relation, and resilient means operatively associated with the ilanged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising metallic piston ring segments, a recess formed in the flanged portions of each of said axially movable bushings, said metallic piston ring segments being received in said recesses.

17. A pressure loaded type intermeshing gear pinnp comprising a housing having a pumping chamber formed therein with an inlet port formed on one side of said housing and an outlet port formed on the opposite side of said housing, said ports communicating with said chamber, intermeshing pumping gears disposed in said chamber, xed body bushings and axially movable pressure loadable bushings operatively associated with said pumping gears, said bushings being radially outwardly flanged, said axially movable bushings being subject to application of discharge pressure to the rear surface of said flanged portions to engage the operatively associated gear side acc in sealing relation, and resilient means operatively associated with the flanged portions of said axially movable bushings for urging said bushings in a direction substantially normal to the axis of rotation of said pumping gears and towards the inlet side of the pump, said resilient means comprising ring segments.

References Cited in the tile of this patent UNITED STATES PATENTS 2,420,622 Roth et al. May 13, 1947 2,444,165 Lauck June 29, 1948 2,527,941 Lauck et al. Oct. 3l, 1950 2,627,232 Lauck Feb. 3, 1953 2,649,740 Murray et al. Aug. 25, 1953 2,660,958 Lauck Dec. 1, 1953 

